Very high variety of combinations of multiple
anomalies may be present, which is at least in part responsible for the
difficulties in confirming the diagnosis. Intrauterine and postnatal growth
retardation and delayed osseous maturation lead to (proportionate) short
stature in approximately 80% of patients. Mental retardation ranges from
mild (common) to severe (rare), but average intelligence has been reported.
Patients are often described as hyperactive with a short attention span
(67%), stubborn, and shy. Muscular hypotonia is common (40%). Seizures
are rare. Craniofacial anomalies may include microcephaly (with head
circumference below the third percentile), premature craniosynostosis,
distinctive, small face with high forehead, flat supraorbital ridge, short
palpebral fissures, scanty or absent lateral part of the eyebrows, lateral
telecanthus, hypertelorism, epicanthal folds, ptosis, blepharophimosis, and
other ocular anomalies (e.g., strabismus, microphthalmia, iris hypoplasia,
coloboma, and ocular albinism). The nasal tip is broad, and the ears are
prominent or dysplastic. Micrognathia (may be severe) and retrognathia
(rare), submucous cleft palate (44%), occasional velopharyngeal
insufficiency, multiple dental problems (delayed eruption, missing teeth,
extensive caries), and a high-pitched and hoarse voice (68%) have been
described. Cardiovascular anomalies are rare but can occur in the form of
coarctation of the aorta, aberrant subclavian artery (dysphagia lusoria),
occlusion of the internal carotid artery, persistent ductus arteriosus,
ventricular septal defect, and mitral valve prolapse. Patients often suffer
from eczema (58%), which tends to improve with age; sparse hair; and
pilonidal dimples. Brachyclinodactyly of the fifth finger is a constant
feature, the joints are hyperextensible, and, patients occasionally present
with scoliosis or spina bifida occulta. Genital abnormalities, such as
cryptorchidism, hypospadias, and inguinal hernia, are common.
Gastroesophageal reflux disease, vomiting, chronic diarrhea, or chronic
obstipation may be present. Bone marrow hypoplasia may occur in up to 6%
of patients, and case reports of fatal aplastic anemia exist. On the one
hand, patients have increased susceptibility to recurrent infections (of
upper airway, ears, and urinary tract, most likely secondary to IgA, IgG,
and/or IgM deficiencies) and malignancies (leukemia, lymphoma,
neuroblastoma, rhabdomyosarcoma). On the other hand, allergies are very
frequent findings.